■602 Proceedings of the Royal Irish Academy. 



Peeissia, Kees. 



Preissia, Corda,in Opiz, Xaturalientausch(1829) ; Xees, Eiirop. Leberm. 

 (1838). 



Dioecious. Fertile receptacle angularly hemisplierical, 2-4 lobed, 

 loculi attached to the under side of the lobes, 1-3 fruited, dehisc- 

 ing irregularly. Colesule obconico-campanulate, 4-5 lobed. 

 Calyptra persistent. Capsule pedicelled, dehiscing by revolute 

 segments. Antheridia immersed in a peduncled peltate recep- 

 tacle. 



Treissia commutata, jSTees. Frond oblong, sinuate, freq^uently bi- 

 lobed at the apex, from 1-3 inches long, varying very much in 

 width, according to locality. Fertile receptacle peltate, hemi- 

 spherical, with keel-like rays. Capsule globose, shortly pedicellate, 

 often of a dark purple colour. Barren receptacle peltate, j)e- 

 duncled. 



3Iarchantia hemisphferica, Linn. Fl. Suec, ISTo. 1052. Conocephalus 

 hemisphsericus, Dmrt. Comm. Bot., p. 113. Marchantia com- 

 mutata, Lindenb. Hep. Europ., p. 101. Preissia Italica, Corda, in 

 Opiz, Natural., p. 647. Preissia commutata, Nees, Europ. 

 Leberm., 4, 117; Gr. L. et IT. Synop. p. 539; Eabenh. Hep. 

 Europ. exsic. n. 5, 125, 141, 330, 481 ; Engl. Bot. t. 2545, 

 exclude figs, at under portion of plate ; Carrington, Irish Hepat. 

 Trans. Bot. Soc. Edin. vol. 7, p. 443. 



Hah. Fissures of damp rocks, and on damp ground in mountainous 

 parts of the country, particularly in limestone districts ; occasion- 

 ally on sandy ground near the sea, as at North Bull, near Dublin. 

 Frequent in Go. Galway. Bocks above Kylemore Castle, and by 

 the side of the lake at Letterfrack ; abundant near Cong ; SiUagh- 

 braes, near Larne, Co. Antrim ; Co. Kildare ; Co. Kerry, about 

 Killarney, &c., &c. The variety minor on high limestone ridges 

 of the Benbulben range, Co. Sligo. Glendine wood, Co. Water- 

 ford, Isaac Carroll, Esq. 



Dfmoetieea, Nees. 



]!klarchantia, Sw. Prodr. Fl. Ind.-Occ. p. 145 (1788). Dumortiera, 

 Nees, in Nov. Act. Acad. C^es.-Leop. 12, p. 1, p. 410 (1823). 

 Lunularia? N. B. in Flora, 13, p. 2, p. 401 (1830). Hygrophila, 

 Taylor, in Fl. Hib. p. 2, p. 53 (1836). Spathysia, Nees, Nat. 

 Eur. Leberm. 4, p. 178 (1838).— Lindberg. 



Dioecious. Male receptacle very shortly pedunculated, peltate, hairy. 

 Fertile receptacle convex, pedunculated, hirsute, with scattered 

 hairs. Colesule wanting, loculi univalved, opening at the top by 

 a vertical fissure at the outer extremity. Frond without pores. 



Dumortiera irrigua, Nees. Fronds large, varying from 2 to 5 inches in 

 length, and nearly an inch in width, membranaceous, bilobed, 

 margins slightly undulate, of a bright lively green colour, and with- 



